Image Degradation with Nikon Teleconverters

A fellow photographer recently asked me how much image degradation one would see with each Nikon teleconverter. As a nature photographer, I have been wondering myself about this for a while, but never had a chance to actually quantify what the image degradation figures would look like when using the TC-14E II, TC-17E II and the TC-20E III with Nikon lenses. I have been relying on field use and my vision so far and here is what I have thought about each teleconverter.

The Nikon TC-14E II is excellent. I have not seen it degrade image quality on any Nikon lenses to the level where I could see obvious loss of contrast or sharpness. I have used it with the 105mm VR, 70-200mm f/2.8G VR (the old one, as well as VR II), 300mm f/4 and pretty much on every expensive super telephoto lens. I take it with me everywhere and mine stays pretty much glued to my favorite Nikon 300mm f/4 AF-S the majority of the time – that’s what I use primarily for birding. When shooting with my Nikon 200-400mm, I don’t hesitate to use the TC-14E II, because it does a very good job sharpness and contrast-wise and AF stays accurate and fast. It is obviously the smallest and the lightest of the three.

The Nikon TC-17E II is a mixed bag. It works with many Nikon lenses, but it slows down AF and impacts AF accuracy. Not as good of a TC to be used with slower f/4 lenses, which includes the 300mm f/4, 200-400mm f/4 and 500mm f/4 lenses. I tried to use it with my 300mm f/4 and it makes the lens hunt a lot, especially in anything but good light environments. The same thing with the Nikon 200-400mm f/4, even with the latest camera bodies like Nikon D4. Because of this, I rarely use mine. On fast f/2-2.8 lenses, however, it does pretty well. It works great on the Nikon 70-200mm f/2.8G VR II and it does not disappoint with the 200mm f/2, 300mm f/2.8 and 400mm f/2.8 lenses.

The Nikon TC-20E III is much better than its predecessor (which was very disappointing with many lenses). I was pretty shocked to see it perform very well with the 70-200mm f/2.8G VR II (stop down to f/8 for best results), because the 2x TC was always known to be bad with zoom lenses. It works like a champ with the 300mm f/2.8 and 400mm f/2.8 lenses. On slower f/4 lenses, however, it is still pretty disappointing. It is unusable on the Nikon 300mm f/4 and 200-400mm f/4 lenses and while it will work with the 500mm f/4 and 600mm f/4 lenses, you will have to stop down to f/11 to get anything reasonably good and you will need to use one of the latest Nikon DSLRs like D4 that can handle f/8 lenses. Not a great setup for fast action, but could work for large animals from a very long distance.

Today, I decided to quantify the loss of sharpness using Imatest. Armed with a brand new Nikon 70-200mm f/2.8G VR II and all three TCs, I set on the quest to measure sharpness without a TC first and then with all three TCs separately at the focal lengths of 70mm, 100mm (1.4x), 120mm (1.7x) and 140mm (2.0x). Here are the results that I got:

For most people, these numbers don’t mean anything. I did the math to figure out the percentages and once I compiled the mean data, here is what I came up with:

Nikon TC-14E II – 5% Sharpness Loss

Nikon TC-17E II – 17% Sharpness Loss

Nikon TC-20E III – 26% Sharpness Loss

Now keep in mind that this is the best case scenario, when everything is stopped down. All four were shot at f/8, ISO 100 on the Nikon D800E. So it is stopping down a lot for the lens alone, by two stops for the TC-14E II (from f/4 to f/8), by a stop and a half for the TC-17E II (from f/4.8 to f/8) and by one stop for the TC-20E III (from f/5.6 to f/8). I figured f/8 would be a sweet spot for all three TCs. The TC-20E III is slightly better at f/11, but by very little. Beyond f/11 diffraction kicks in and you start seeing image degradation instead of improvement.

As you may already know, maximum aperture changes when using teleconveters. If I shot these wide open, the numbers would be totally different. All teleconverters behave differently at maximum aperture, with the TC-14E II having the least impact on sharpness and both TC-17E II and TC-20E III having the most (I would say both are fairly soft wide open, depending on what lens you mount them on). Also keep in mind that this test only shows performance on one lens – TCs vary in performance on different lenses. You can expect both the TC-17E II and the TC-20E III to behave differently (better) on fast prime lenses like 200mm f/2, 300mm f/2.8, etc.

In summary, when using teleconverters in the field, you could expect the 1.4x teleconverter to lose about 5% sharpness, 1.7x to lose 17% and 2.0x to lose 26%. The TC-14E II is a no brainer here – with only 5% sharpness loss, you won’t see any difference between the original and with the TC attached. All three will look great if you are down-sampling, but differences will be visible when doing 100% crops. For birders, this means that you might not see that same level of detail on feathers and hair that you would see when using the lens without any TCs, or with the TC-14E II attached.

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About Nasim Mansurov

Nasim Mansurov is a professional photographer based out of Denver, Colorado. He is the author and founder of Photography Life, along with a number of other online resources. Read more about Nasim here.

Reader Interactions

Comments

1) Stefan

April 7, 2013 at 7:18 am

Thanks, Nasim! This info helps a lot. Sometimes it’s hard to realize how much the TC affect the image sharpness. But they do. Now, time for some decisions…. :-)

Nasim, is it a possible to put next to each other the 70-200 f/4; 70-200 f/2.8 and 80-400mm – just for size comparison. And may be you will add something more… I want to get the 80-400, but I’m a bit concerned about the bulkiness of the lens. As it is bigger than 70-200 f/2.8. For most of the occasions I’ll use 70-200 range, but is it worth for those few times I’ll need the 200-400mm to carry the extra weight and size (and price) all the time?

The size and weight differences between the 70-200mm f/2.8 and the new 80-400mm are negligible. If you are used to carrying the 70-200mm f/2.8, you’ll pretty much have the idea of what it is to carry the new 80-400mm.

Stefan, absolutely – will do that while reviewing the Nikon 80-400mm. I don’t have the 70-200mm f/4 anymore, but I will put the 80-400mm, 70-200mm and 200-400mm side by side for a size comparison :) The 80-400mm is surely bulkier than the 70-200mm – the barrel is thicker and the lens is longer when fully extended at 400mm.

Stefan. The new 70-200mm f/4 is just as fast of the f/2.8 VR2. Last week l went to a dog show and the lens perform very will on my D3s. I took all pictures at full aperture and the focus was accurate all time, fast without hesitation. I was looking for a lighter model of this lens and believe me, you won’t be disappoints. And l have a studio and again this lens is so sharp for portrait.

Thanks, Jean! That’s very good to hear. I love my 70-200 f/2.8, but sometimes it’s too heavy, especially to carry with me and use for landscapes. I had 70-300 before, but it’s soft after 220-240mm. How is the f/4 version with the CA and color fringing? In your opinion, do you need the collar to attach on a tripod, or it is small and light enough to hang on the body (I’m with D800).

The color fringing just like the f/2.8. And no need of a collar because the f/4 is 50 grams lighter of the 24-70 f/2.8 who didn’t not have a collar. So if you need to attach a tripod, you can do it directly on you camera body. By the way, l use this f/4 in studio with my D600 (camera body for studio and D3s for outside) and give me amazing results.

Thanks for sharing, Jean! Also this new f/4 has one extra stop VR if I’m not wrong.? Do you see any (big) difference in DOF when use this lens in your studio? Should the bigger DOF (compared to the 2.8) be a concern?

l’am able to shoot at 200mm and 1/20 sec. with the new VR. It just fantastic ! In studio, it so sharp and use it more and more handheld. With my D600, it give me great results and at 200mm at minimum distance, the f/4 still a real 200mm but the f/2.8 VR2, was given me more a range of 160mm.

I have not shot too many pictures so far with the 70-200 f4 using the TC-14 EII, but the combination has worked great with no focus issues and really excellent image quality (using a D7000). Not surprisingly a tripod definitely improved image sharpness and therefore a collar is very handy. I found that there is significant “vibration” when the tripod is attached to the camera, which is eliminated when the collar is used. With above camera/TC/lens combination mounting the collar “backwards” results in a well balanced system and superior IQ. The collar also allows the use of a monopod, which in my hands also noticeably improved the IQ compared to handheld. The monopod approach allowed me to take the exposures needed for an HDR image at the longest tele length, which I can’t do handheld.

Thanks Nasim, I’m converted lloll (to the 1.4). Also great exchange here! I love my little 70-200. I say it again, I have the chinese collar on monopod and it’s great for the money! But is sleeping Nikon going to wake up any time soon and release the 300 f4 VR?

I’ve used the 70-200mm f/2.8 VR II and TC-20E III combination on a D600 to shoot soccer and car racing, and AF has been fast and accurate. These have been in daylight and overcast conditions with good amount of natural light. I still have to try that combination indoors and in the nighttime with artificial light. I don’t expect it will excel in those conditions, though.

Jean, I am glad that you are enjoying your 70-200mm f/4G – it is a great lens! As for a TC for the lens, while it will take all three of them, the 1.4x TC works the best. If you have the latest Nikon cameras like D7100, D600, D800 or D4, then the 2x TC will also AF, but sharpness is not great wide open at f/8, which means that you will have to stop down to f/11 to get good results…

Even if l’m in Quebec City and my first language is french, l follow all your articles for a more than a year and half. And l have a D3s for wedding (ambient light), sport and a great D600 for my work in studio. It’s always a pleasure to follow you and read your review.

You say that TC-17EII makes the 300 f/4D hunt and the TC2oEIII us not usable at all. I think this was the case for prev-gen bodies s (D300/D700/D3s). The new bodies (D4/D800/D600/D7100) should be able to focus at f/8 and perhaps perform better at f/6.8.

I have 300 f/4D + 1.4x and I am quite happy. A while ago I rented also the TC17EII, got a few very good pics with it under good light, but it was indeed hunting a lot.

I have recently upgraded my body from D700 to D600 and I am thinking if I can upgrade the TC to 1.7x to get even more reach. According to the docs all 39 AF points should be working up to f/6.8 (that is 300 f/4D + TC17EII) and 7 inner points should be working even at f/8 (300 f/4D + TC20EIII).

Could you please update you article whether these new f/8 focusing bodies make the situation any better?

I have used the 1.7x in combination with a 300mm f2.8 and D300 and found it very good if not excellent in good light. On changing to a 500mm f4, I left the 1.7x in the bag unless I wanted a record shot of a static bird at range mainly due to image degredation though, the AF speed was poor.

With the D4, both IQ and AF speed are improved BUT, IMO the 1.7x is not an ideal choice for an f4 lens and I will not be using it very often. That is to say, if I did not already have it, I would not be getting one.

MPE, no, I have also used the TC-17E II and TC-20E III with the 300mm f/4D. While AF works at f/8, it is not accurate and sharpness suffers greatly. AF speed also suffers. I still do not recommend to use either one of those on lower-end f/4 lenses, especially zooms like 200-400mm f/4.

Dear Nasim, Thanks for this and your many excellent reviews. So, when birding with the 500mm f/4 and a D800, would it be better to use the 1.4x and crop as needed than to use the 1.7x or 2.0x TCs with less cropping? Joel

To me this is the most relevant question here. Any thoughts anyone? So in other words, if you are going to crop to a certain size anyway in post processing (eg to fill your picture with a bird), would you get a better result with the TCE14 and cropping or the TCE20 and less cropping?

With the 500f4, I don’t even take my 2x TC . I understand the MKIII version is better than the old older models but is still not recommended for f4 primes.

The 1.7x works well in good light with the D4 and 500f4. In poor light, it will slow AF considerably. There is no point in having the reach if you cannot attain focus.

With the D4, the 1.4x is excellent. If you have the D800 you have more scope for cropping than I do. If you are thinking of buying only 1TC to use with an f4 prime, sticking with the 1.4x is the best option IMO.

Joel, I apologize for a late response. In my opinion – TC is way better than trying to crop. The reason for this, is that the shorter TCs like TC-14E II lose very little sharpness. And with the added 1.4x focal length, you have more options to crop, with practically no IQ loss. With longer TCs, loss of resolution is only one of the variables. As Colin stated above, both AF speed and accuracy are impacted when using 1.7x or 2x TCs on f/4 lenses. So the question of “is it better to use a TC or crop later” gets a little more complex. I would rather have a very sharp image that I can crop, even if too aggressively, than a soft/out of focus shot that fills the frame. Keep in mind that good handling technique becomes increasingly important when you increase the focal length of the setup. So to sum it up, use the 1.4x TC with your 500mm to get the best reach and remove it when reach is not an issue. Try not to use the 1.7x or 2x TCs for birding, they slow down AF and impact AF accuracy. If you had a static subject that does not move, then longer TCs could certainly be considered, provided you can secure the setup on a stable tripod and stop down to f/11…

Thanks much! This is clear and straightforward… I appreciate your feedback on this question of TC image degradation. Would you think that the TC 1.4 is ok to mount on the new 80-400 G ? Chris. (Reading you from France)

Chris, yes, the TC-14E II works with the 80-400mm and from what I see so far, there is little impact on IQ in bright conditions. I will be testing the lens extensively and will let you know what I think about all three TCs with it in my upcoming review.

The new 80-400 against the 70-200 VR II with TC-14 (which would make it a 98-280 lens). If you want to test the 70-200 with the other two TCs against the new 80-400, that won’t hurt either, but from the above #s I don’t see much point.

Hey Nasim, Thank you for enlightening us regarding the teleconvertors.. The article is bang on. However it could be great if you can share some image comparisons while depicting the sharpness loss. The percentage gives a fair idea, but some pictures would be great. Thanks

I had the same question and made some tests with a D800 and a 70-200 VRII. Without a doubt the tested TC-17II was much better compared to the crop with regard to the resolution (340 mm vs. 200 mm crop). You can see much more detail and less pixels on the image taken with TC. On the other hand the contrast needs a bit post processing.

Kevin, TC will always win compared to a cropped image. Think of it as a longer lens – what is better, a 200mm lens cropped, or a 300mm lens without any cropping? The latter wins, because it still gives you the option to crop and you have the advantage of down-sampling images. Now with TCs longer than 1.4x, there are other factors to consider, such as AF accuracy and speed – see my response #60 above, where I talk specifically about this. The TC-14E II is pretty much a no-brainer for any lens that can take it…

Thanks , take your point . This and other comments have convinced me to get a TC – 14 E 11 to go with my 70-200 f4 . Hope this is not a silly question but should one put the TC on the Lens and then mount the combination on the Camera OR put the TC on the Camera first . ?

Given this information, when would it be better to tele-convert or crop? Say I’m sitting in Yellowstone with my D4 and 200-400 f/4 looking a a wolf in the viewfinder and it is a bit smaller than I want at 400mm. Attaching a 1.4 is better, but still too small. Attaching a 2.0 is perfect for image size that I want. Now, from a sharpness standpoint, would I be better shooting with no converter and making a big crop? Shooting with a 1.4 and making a smaller crop? Or, shooting with the 2.0 and having to make no crop? I know it’s a theoretical situation and other factors might come into place; but just think about it as it is. I’ll be interested in your comments. Thanks!

From what I have observed and read about the 200-400, it is not really a good lens to use with a TC. You should crop. Note that when you add a TC20e III to an F4 lens only the centre AF point will work.

I have been using the 500mm vr lens for several years for birding, and I have used all the three tc’s. I totally agree with your findings.

For the 500mm vr, the best setup is 500/4 + tc-14e at f/8. At wide open, I can surely see small difference in sharpness compared to that when stoped down, but at f/8, I can not see any sharpness or contrast loss.

I never quite liked the performance of the tc-17e with 500mm vr. Even though it is a pretty good tc, not as good as the tc-14e both in sharpness and contrast.

For the older version of the tc-20e, I sold it after a few try, and never attempted for the new version since the aperture at f/11 is very hard to manage.

Also, I should say that if a tc is to be used with a telephoto lens, it is always better to use a full frame camera. For example, I use d600 with 500/4 + tc-14e combo at f/8, and the iso sometimes goes as high as 900, or slightly above, this is no problem with d600, especially at iso 400, the d600 is very clean, and iso 400 is where I usually stay with tc-14e.

The 500mm/ 1.4x combo at f8 works well with the D300 and even better with the D4. In fact, it is so good with the FX sensor, I only take it off if the light is very poor. With the DX sensor, I only put it on if the light is very good due to fall off in AF speed.

I would add, for anyone with or thinking of getting the 300mm f2.8, the 1.7x works very well. It’s a stellar lens but IMO just not long enough naked for birding in general.

Please help me know what will be best for photography of small bird out of Nikon 500 F4 G ED VR ii +1.4x TC OR Nikon 400 F2.8 G ED VR ii + 1.7x TC. I am a D800E user and previously used Sigma 150-500 and then Nikon 300 F4 IF ED+1.4x TC with D800E.

You state that if a TC is to be used, it is always better to use a full frame camera. Not true. The DX sensor always uses the sharpest Center of any lens and TC combination. Nasism’s graphs above illustrate this clearly. The degradation is always greatest on the edges of the frame, which the DX sensor never uses. The additional 1.3x crop available on the new D7100 uses the very sharpest center of the lens, so using it with a TC would result in even less image degradation. So, when using a TC, it is actually always better to use a DX camera, especially one like the D7100 which supports AF at f/8!

No. Teleconverters achieve the reach by magnifying the central portion of the image.

If you use the TC on a fullframe camera, you are also using the best part of the lens. True, the resolution of any lens degrades towards the edge and that gets magnified too.

The reason why TCs work better on FF cameras is that typical pixel density of FF is usually lower. The TC works best if the lens outresolves the sensor and thats likely to happen on lower pixel density sensor.

I stand by my original post. Under all circumstances, an FF lens used upon a DX body will always be using the sharpest center of the FF lens. When you then add any TC to that combination, you are then magnifying the center of that sharpest center of the original lens. The closer to the center of the original lens, the sharper the image. It’s basic physics.

The TC on a fullframe camera is not exclusively using the SAME best part of the lens. It is including and also using and magnifying the slightly less sharp area that is 50% larger than portion used by the DX frame.

The TC works best when the original portion of the lens it is magnifying is sharpest. The TC on a DX body is magnifying the VERY sharpest center area of the FF lens than the same TC on an FX body, which is also magnifying a larger, slightly LESS sharp area of the same lens.

The pixel density of the D7100 at 24 MP is the same as that of a D800 at 36 MP. The pixel density of the D7000 at 16 MP is the same as that of a D600 at 24 MP. So, the “typical” pixel density of FF is no longer lower, and TC’s best use will always depend upon the quality of the original lens. As Nasim’s graphs above demonstrate, lenses are always sharpest at their centers, with sharpness falling off the farther away from the center being magnified. DX bodies always use the VERY the sharpest center of the lens, which when magnified by a TC, will always be slightly sharper than the same TC on the same FX lens on an FX body.

Phil, I understand your statement about the center sharpness of the frame, and the advantage of the dx sensors because they use this center portion. However, many times with fx cameras, the objects in photos are localized around the center or at the center anyway, so this should not make much difference. After all, a dx sensor is just a crop of an fx sensor.

In terms of tc usage, what really matters is the iso performance. When a tc is attached to any lens, the effective aperture drops. In addition to this fact, usually another stop has to be sacrificed to compansate for the acuity losses. Put it all together, good iso performance is necessary at long focal lengths with fast shutter speeds. This is why I think the fx cameras are more suited for tc use.

you are not entirely correct when you say that that pixel density of D800 is same as D7100 and D600 as d7000. In fact all Nikon DX cameras in production have higher pixel density than any FX camera ever made. (D3200, D5200, D7100 have 6.59 MP/cm² while highest pixel density FX (D800) is 4.22 MP/cm², only the D7000 is close to D800 but still a tad higher with 4.39 MP/cm²). D600 and D4 have both significantly less pixel density that any of the above and even lower than old D200 for example. You can roughly compare pixel density when you check what is the resolution of the camera in DX crop mode.

1.4x converter magnifies area that is just slightly larger than DX crop so it is magnifying also the best part of the lens as well. 1.7x and 2x are magnifying even smaller portion of the frame. The reason why you see drop in corner performance is that the teleconverter is a lens too. However, I don’t think that most people care about corner performance of a lens with TC unless shooting very specific subject. On my pictures with long lenses, corners are always out of the focus.

You can’t say that any lens perform better on DX as it is using the best part of it. FX and DX stresses the lenses in slightly different way. DX is demanding for resolution due to high pixel density and on FX it is often more important optical parameters like vignetting, distortion or spherical aberration. That’s why some lenses perform better on FX than on DX while others shine on FX. Typical example is venerable AF-D 20mm, that.

A teleconverter works best if the lens outresolves the sensor and it is likely the case on FX.

Photo Phil, the debate of DX vs FX for wildlife and sports is a never ending one. DX shooters will always argue that DX cameras give the best reach, while FX shooters argue that they get less noise at 100% crop. I have shot with both and I take side with the FX guys and here are my reasons: 1) DX cameras typically have smaller pixels than FX cameras (the only exception to this is the D7000, which has about the same pixel size as the D800). This means several things. At pixel level, DX cameras are more demanding on optics, which is not always good, especially when using teleconverters. TCs do impact sharpness, as shown above, so if the lens + TC combo cannot resolve the full detail, you won’t be happy with the sharpness at pixel level. On top of that, smaller pixels also mean a lot more noise at pixel level. Compare 100% crops at ISO 100-800 on a DX camera to FX and you will see exactly what I mean. FX will produce noise-free images at ISO 100-400, while DX will have noise, especially in the shadows, even at ISO 100! This means that you cannot really crop DX to 100% in many situations. If you do, you have to apply proper noise reduction to get rid of all that extra noise. On FX, you don’t typically have to worry about noise. 2) Sure, DX sensor crops out the worst part of the lens, but who cares about that on super telephoto lenses? Take a look at MTF data for most super telephoto lenses – they all look excellent in the corners. In addition, I do not know of any wildlife / sports photographer that cares about corner performance. Most of the shots will have the subject in the center or slightly off-center. Nobody will take a shot of a bird in the extreme corners of the frame. So the crop part of the sensor is irrelevant, DX has no advantage here whatsoever. 3) FX cameras have much bigger viewfinders than DX. This makes it a whole lot easier to see if the bird you are photographing is indeed in perfect focus. With DX, you have to rely on AF a lot, because you just can’t see that well through the viewfinder. 4) In my experience, the MultiCAM 3500FX works better in terms of AF accuracy than MultiCAM 3500DX. While a lot of people argue that both AF systems are the same, having shot with both for a long time (I used to own a Nikon D300) I disagree. In my experience, MultiCAM 3500FX is better than MultiCAM 3500DX. I think it has to do with the fact that FX cameras have a much larger mirror and hence the AF system might receive more light from the lens. Try shooting birds in low light with both the D300 and the D700 (or with the D7100 and D800), and you will quickly realize which camera will end up with better AF accuracy. Hence, my conclusion is that AF on FX bodies is slightly better than on DX. There might also be size differences between 3500FX and 3500DX. If the AF modules for both DX and FX were exactly the same, Nikon would not have named them differently. I noticed the same thing with the D600 and the D7000. The former has the same module as the D7000, albeit modified for FX. I did some birding with the D600 and the D7000 and I came back with more keepers on the D600 than I did with the D7000. Perhaps I am biased towards FX, but that’s my “real world” experience. 5) Those who try out FX for wildlife almost never come back to DX. Some people shoot with both, but if you ask those that do, they will tell you that they prefer their D3 to their D300/D300s. FX makes a difference, whether it has to do with image quality, AF accuracy or other reasons. 6) DX was never designed as a “feature” for getting closer to action, as I numerously pointed out in my articles. If digital sensors did not cost so much money in the past, manufacturers would not have made DSLRs with small sensors. APS-C was designed for cost reasons alone, to make DX cameras cheaper, not to make DX cameras lighter or better for reach. 7) As of today, Nikon could easily make a full-frame camera with the same pixel pitch as the D7100, which would result in a 56+ MP full-frame camera. In order to keep the fps speed high, they could easily make a “DX” crop mode that shoots at the same speed as the D7100 (if not faster). This basically means that an FX sensor can have all the features of a DX sensor in one package. The only advantage of DX today is cost. But with such offers as the D600 and the price of FX sensors continuously coming down, that huge cost difference is not there anymore. If in the past you had to spend 2x+ to move up to FX, today that difference is much smaller. Manufacturers are now making feature differences between cameras and intentionally removing functionality from FX cameras like D600, so that their high-end DX lines are not threatened. Can you imagine what a D600 with a MultiCAM 3500FX + 1/8000 shutter + big buffer would do to the D7100/D300s sales? With recent promotions, the D600 dropped to as low as $1800 and the price is going to continue to drop. That’s why I believe that DX has no future. Nikon might try to push a D400 later this year, but it probably will be the last high-end DX camera we see from Nikon. As soon as the D600 gets a 51 point AF and a bigger buffer, it will be the end of the high-end DX.

In summary, FX is better than DX for shooting wildlife and sports for the above reasons, so I have to agree with both Goker and MPE here :)

What a wonderful compilation of exactly what I have been missing! Thank you all! I stand corrected, and MUCH better informed. Independently, last night, I found out that a previous DX only bird shooter, whose images have always been spectacular, had switched to the D4 last year, and had no further interest in DX when I asked about any interest in the new D7100. They had to switch to the 500mm f/4 from the 200-400mm f/4 to compensate for the loss of reach, but the image quality is stunning and the keeper rate is higher than ever before. They now want a D4 with an even FASTER frame rate!

Nothing beats real world experience. Brighter viewfinders, faster and more accurate autofocus, better low light performance to keep shutterspeeds up and noise down, and better TC results are all compelling reasons to prefer FX over DX.

So, putting all the above information into action, with the original 200-400mm f/4 VR and both the TC1.4E and the TC2.0E III to choose from, with available bodies of the D300, D700, D7000, and D7100, for maximum reach at the best quality, would you still only use the D700 with the TC1.4E on the 200-400mm f/4? If using DX, would you prefer the D7000 over the D7100 because of the larger pixel size? Or perhaps the D300?

Similarly, which body would you use on the original 70-200mm f/2.8 VR when using either the TC1.4E or the TC2.0E III? Would you expect better results from a cropped D700 image than the uncropped D300, D7000, D7100 combinations?

Is the TC1.4E good enough to use on the 200-400mm f/4 all the time on the D700, instead of the bare 200-400mm f/4 on any of the DX bodies? Which DX body would produce the best image quality among the three DX bodies on the 200-400mm f/4? Which DX body among the three would produce the best image quality if combined with the TC1.4E on the 200-400mm f/4?

Also, in which of the above scenarios would you recommend stopping down from one stop below wide open to TWO stops below wide open, under each combination, for maximum sharpness and detail?

Yes, absolutely – I would pick the Nikon D700 any time over any other DX camera. Couple the D700 with the TC-14E and the 200-400mm f/4 and you get yourself a superb package that will produce killer images. I have been using exactly this setup for a number of years now and I love it. I will never sell my D700, it is without a doubt one of the best Nikon DSLRs produced to date. If I were forced to use DX, I would probably buy the D7100, simply because it has the newest technology and it will have a good resale value for another year or two.

As for the 70-200mm f/2.8, again, I would use the D700 with or without TCs. And yes, I know that I can get better images from my D700 than I can from the D7100. At least I never have to worry about noise at low ISOs and I can fully rely on the AF system for those critical moments of action.

The TC-14E II is superb on the 200-400mm f/4G – I use it all the time. Bare 200-400mm will give you a stop more of light in situations where you need to push ISO and the shutter speed, but it is typically not a concern for the D700.

As for maximum sharpness, shoot the 200-400mm f/4G wide open, whether with or without the TC-14E II. I never stop down mine, unless I need to increase the DoF for a close bird.

One suggestion though, if you are serious about birding, get the 500mm f/4 VR instead. The 200-400mm is good for bears, but I prefer the 500mm f/4 VR for longer reach and versatility instead. The 500mm f/4 + TC-14E II gives you 700mm f/5.6 and you cannot get to 700mm with the 200-400mm.

It helps immensely! Thank you! Looks like my D700 will become my new “go to” camera for the 200-400mm f/4 with the TC-14E II permanently attached. When I want to travel light for distant subjects, I’ll save the new D7100 for the 70-200 f/2.8 with the TC-20E III attached, and shoot at f/8! Otherwise, I’ll use the D700 on it and all my wide angle lenses, too! Now, I just need to scrape together $8,400 for the 500mm f/4G VR upgrade, and another $6,000 for the D4 upgrade, to keep up with my other mentor! This hobby has become the most enjoyable money pit I know, where you truly get what you pay for! It’s some consolation that the glass at least holds its value! :)

One more thing to add to this – the 200-400mm is great for close action, but it has IQ problems at long distances (misses focus too much). I hate taking my 200-400mm with me to Yellowstone to photograph bears and wolves because of this. So keep this in mind. The 500mm f/4G has no such issues and its overall IQ is better.

According to Nikon, all three TC’s (14E II, 17E II, and 20E III) work with the new 80-400mm with AF limitations. What is kind of weird is that Nikon says that AF will work with bodies that support AF at f/8. The TC-20E III paired with the 80-400mm will produce a maximum aperture smaller than f/8 at any focal length, so IMHO Nikon should have listed that combination as AF not possible.

It’s always a pleasure to read your articles. Here’s my comments: You’ve done a very good technical analysis on those converters. I’ve got a 70/200 f2.8 as well as a 300 f4 on my D300s. The TC1.4 works well on both lenses. The TC1.7 degrade the quality of picture on the zoom lens but I still find it good on the prime lens and the system doesn’t hunt at all on both lenses. I’ve tried the TC2.0III on the prime lens and the system still works though the quality is degraded.

Louis, I might have different tolerance on what is deemed “acceptable” by other photographers. For me, if I zoom in to 100% and I don’t see all the details, I am not happy. The TC20E III is superb for some lens combos, but it is not sharp until stopped down to f/8-f/11. The TC-17E II is a mixed bag for f/4 lenses and while it can work in good light, it will surely slow down AF speed and accuracy. It also needs to be stopped down to get the best sharpness. For some people, 70-200mm f/2.8 + TC-20E III looks sharp wide open. I am a lot pickier when it comes to sharpness, so I disagree with them and say that f/8 is pretty much required with that combo to get acceptably sharp photos.

I would be interested in the experience people have had comparing a prime lense with a TC and using a longer zoom. For example, starting with the 85mm f1.8 and using the TC 1.4, TC1.7 and TC 2.0, how would the results compare to the 70-200 f2.8 at the matching zoom. Thanks,

Okay, but I’m only using this as an example. Take a prime lense which is compatible with TC’s and compare the results with a high end zoom which covers the same resultant focal length. The essence is the question, is it better to work with a prime and use TC’s or use a zoom to cover the same range. Thoughts … Thanks.

I do not think there is a definite answer to this because how well it works depends on the lens, lens aperture for focussing purposes, focal length, light, sensor size, and pixel density. It also depends on how still the subject is. A D800e with a still subject would probably produce a better result if you cropped when compared to a D90 with a TC. I use a D800 and when the focus is spot on the resolution and therefore cropping options are amazing. The issue is making sure the focus is exactly right.

Martin, Thanks for the post. Very interesting. I wondered if, with camera’s like the D800, we have reached a point where you can get better results from using higher performance shorter prime lenses and cropping, or using the traditional zoom. Even if its a high quality zoom. Do you think we have, at least in some situations. Thanks.

I use longer lenses for bird and nature photography. Sometimes the subjects are close and at other times they are some distance away.

It is true that with the D800 I can take a picture of a person, then open the image then zoom in on the eye and see reflected in the pupil all the details of the room behind and around me. The D800 has so much resolution the detail available is amazing.

I have however taken pictures of birds in the jungle with a TC20E III and the 70-200 VRII on a D90. In a couple of cases the birds were so close that I had to pull back to 70mm. The level of detail holds up very well on a 13×19 print (Epson R3000). WIth the D800 I now use the 300 F4 with a TC1.4II. The level of detail can be amazing. I like to carry lenses to cover several scenarios. If I only have time to use the 70-200, but a longer lens would have been preferable, I know that I can crop.

Having said that, I don’t think I would be as happy just working with my 85mm 1.8G as I am with the 300 when dealing with subjects some distance away.

exactly, some lenses seems to give better results with TC than some others … A review of associations of pro lenses and TC based on accurate measures would be wonderfull because NIKON dont give any MTF chart on that.

I frequently used my 70-200mm f/2.8G VRII with the TC-20E III and D7000 on a tripod for wildlife shots. To me I feel they are a great combination. However I have to bear with the dropped f-stops of f/5.6. Seldom I slow down to f/8, well, will try this sweet-spot next time.

Flores, no, there is no typo. What I am trying to say here, is that the TC-14E II already slows down the lens to f/4, so jump from f/4 to f/8 is two stops. For the TC-20E III that slows the lens down to f/5.6, stopping down to f/8 is one stop. Hope this clears it up :)

Hi Nasim, Great review on TCs. Actually i ve been waiting for this one for long. I am an amateur and love nature photography. I am looking for a long range ( 500 to 600 mm) for some time for occasional use as a result i do not want to spend too much on such a lens. Reading your article looks like nikon 300 f/4 with TC 1.4 would be a good option for my nikon D4 rather than going for a sigma 150-500 or tamron 200-500. TC 1.4 also should work with my 70-200 VR II it seems.

I absolutely love the 300mm f/4 + TC-14E II combo – that’s what I have used for the majority of my wildlife shots. If light conditions are good, the TC-17E II can work out OK, but the AF speed and accuracy will still suffer for birds in flight. I have tried the Sigma 150-500mm and it is nowhere as good as the 300mm f/4 + TC-14E II optically. Haven’t tried the Tamron, but it is probably about the same as the Sigma.

I have used the old 1.4 on my 80-200 and 3002.8, but have actually found the old 2X converter to be very nice on my 3002.8 with my Nikon D600. The extra range definitely makes up for some sharpness loss.

While shooting birds, move closer is not always an option, so being able to get them to fill the screen enough for a good focus makes up for some sharpness loss. I would love to see what the new 2x would be like on this lens.

Zapp, the new TC-20E III is much better than the old one. Give it a try and you might keep that 2x permanently mounted on your 300mm f/2.8. Stop the lens down to f/8 and you get quite a lot of feather detail, which is nice.

Jychong, in my experience, the 300mm f/4 + TC17E II combo works, but the AF speed and accuracy suffer greatly, especially in less than ideal lighting situations. I tried it shortly with my D800 and I was not excited with the number of keepers. Some shots came out OK, but I was a lot happier with the 300mm f/4 + TC14E II + some cropping.

Hi Nassim, Thanks for your reply. You are definitely correct that with the 1.7X TC, AF speed does suffer. From my own personal experience, I have shot with both the 1.4X TC and 1.7X TC and have come to prefer the 1.7X TC for the extra reach. In the field(and I shoot very BIF very regularly), I find that 510mm does add a bit more magnification vs 420mm for bird photography. I mostly stop down to F8 so I do not lose too much sharpness. Call it my naivety or stubbornness(or both!), I still prefer 1.7X TC over the 1.4 and have probably gotten so used to it I do not really want to switch back.

I actually have a pretty good “hit-rate” with this setup. But having read your article maybe I should revisit the 1.4X TC again? I am very interested to know about your findings for the 1.4X TC on the new 80-400 since that is something I am also considering.

Hi Nasim, Thanks for this very useful review. However, “sharpness” is not the only thing to consider. A teleconverter obviously gives you a bigger image but does it reveal any more detail than merely upscaling the image from the bare lens to the same size. If no more detail is revealed then it is pointless to use a TC. I recently did this test using all three Nikon TC’s on a Nikkor 300mm f4 and a Nikkor 300mm f2.8 VR2 on a 24Mpx DX sensor (d3200). On the Nikkor 300m f2.8 successively more detail was resolved as I worked my way up through the TC’s. So, as you say, the image was less sharp but more and more detail was revealed. On the Nikkor 300mm f4 it was a different story. The TC14E revealed slightly more detail but the TC17E and TC20E did not. Hope this adds to the thread. Regards, Keith

Hi Colin, All lens/TC combinations were tested at 1 stop down from wide open. So for example with the 300mm f4 the tests were at f5.6 for the bare lens then f8 with the TC14E, f9 with the TC17E and f11 with the TC20Eiii. With the 300mm f2.8 I only tested with the TC14E and the TC20Eiii. So the apertures were f4 bare lens, f5.6 with the TC14Eii and f8 with the TC20Eiii. The rationale was that each combination was tested at or near the “sweet spot”.

I don’t know enough to get deep into the physics of this but, as I understand it, diffraction can impact on image quality to an increasing degree as you stop down. Also, the problem increases as you increase the number of pixels on the sensor.

I seem to recall that with the 12MP DX sensors diffraction was kicking in around f11 so I would expect its effects to be impacting on IQ rather earlier with the 24MP DX sensor. Hopefully, Nasim will get an opportunity to put me right on this but, I would have though a fairer test would have been to shoot all at the same aperture.

In any case, I think we are agreed that in general, the f4 lens are better suited to the 1.4x, although as I said in another post, the 1.7x works well with the 500f4 with the D4 (but not the D300) and I would happily use it in good light if I wanted the extra reach.

Thanks for a really thought-provoking post. And, thanks to Nasim for the article.

Colin, you are right – diffraction does impact image quality very quickly as you stop down. Try to photograph something at f/8, then stop down to f/16 and compare images. Diffraction is very visible at pixel level. On DX cameras, diffraction kicks in at f/8, but only gets visible at f/11 and smaller. On FX cameras, you won’t see it at f/8-f/11, but it is visible at smaller apertures. As for diffraction increasing with smaller pixels, there are two schools of though regarding that. Some people argue that pixel size has no effect whatsoever on diffraction and that it is purely a matter of sensor size and aperture (there are a number of articles and research material on this), while others will say that pixel size does play a role. I stay in the middle – my opinion is that diffraction does not increase with smaller pixels; it only becomes more visible. For example, if you start seeing diffraction on a 12 MP DX sensor at f/11, doubling the sensor resolution might show signs of diffraction at f/8. It does not mean that the smaller pixels caused more diffraction – it simply means that you are seeing more details now at pixel level, which reveal the fact that APS-C sensors are prone to diffraction at f/8. It just becomes more visible. If you went the other direction and decreased resolution, you might not even notice it at f/11. According to what I see from Imatest results, diffraction starts showing up at f/8 on DX bodies and at f/11 on FX bodies on high-resolution sensors such as D7100 and D800.

Keith, I agree with your assessment – that’s why I do not recommend to use either the TC-17E II or the TC-20E II with the 300mm f/4 or 200-400mm f/4 lenses. Like I mentioned above, it is not always about the detail either. In less than ideal conditions, f/4 lenses will hunt a lot and AF accuracy and speed suffer greatly. With f/2 – f/2.8 lenses, the longer TCs work great and resolve plenty of detail. Yes, good images can be made with the 1.7x TC on the 300mm f/4 like Jychong showed above using the latest generation Nikon DSLRs, but the number of keepers is very low for my taste. I would not hesitate to use the 1.7x and the 2x TC on the 300mm f/2.8 though – those combos work quite well.

Terrific article by Nasim (succinct, precise, detailed), great postings, and wonderfully comprehensive responses from Nasim, all presented in a mutually considerate and discussive manner. THIS is what makes Mansurovs/Photography Life such a great site. Thanks to all.

Clearly. I’m saying nothing new when I declare that I have the 300f4/TC14E combination, and , to my mind, it is the best bargain in the entire Nikon line-up. The TC14E virtually never leaves the back of the 300f4. It is a stunning 420f5.6 on a D700, D800, and D3s, (I usually set aperture priority f8 as a matter of course) and the combination is relatively compact and portable for wildlife. The combination fits (just) inside the 300f4 case.

Thank you all for the great posts. Is there anyone who has had experience with the Nikon 200mm f2 and Teleconverters? I really need the f2 for theatre but would love to have good results at 400mm with the tc20eiii. I pray for a classic Mansurov review of that lens and the possible versatility using tc’s.

Billy, that lens will work with anything you throw at it :) Seriously, it is probably the sharpest Nikon telephoto lens. With the TC-20E III, it becomes an f/4 lens – stop it down to f/5.6 and you will get amazing sharpness with it.

I have just read your article again and noticed that your test was carried out at 70 mm focal length. Did you have a reason for this as, logically, one would tend to use the TC’s to increase the longer, not the shorter focal lengths. Is that correct? Would the same results be achieved if tested at 200 mm focal length?

Thank you for your reviews and comments as always. I purchased 70-200f4 VR based on your recent review for the same and this is my second lens ( 1st waz 50mm 1.4G) purchase after reading your reviews. Thanks for the same!

I was wondering if you have some experience on Kenko TC 1.4 Pro DGX 300 with the above 70-200mm lens ? I was getting this TC in immediate future and wanted to know if you can advise something on it. Will it be same or diffent than Nikon TC 1.4eII?

Nasim Many thanks for your great website and useful advice. I am looking to purchase a Nikon telephoto lens reaching around 400mm for wildlife use on a D800, with tripod & cable release where possible; a fast prime would be very nice, however my budget is around US$3,000. My longest lens at the moment is the 24-120 f/4 (purchased after reference to your comments – thanks). Choices seem to be (1) the new AF-S 80-400 VR; (2) AF-S 300 f/4 + TC-14EII; or (3) AF-S 70-200 f/2.8 VRII + TC20EIII. (1) seems good by initial reports on the web; (2) seems to be the cheapest solution albeit lacking VR; (3) seems would be less sharp at 400mm than (1) and (2), but offers a faster speed and good IQ up to 200mm. Do you think (2) is a good match for the D800 in terms of achievable image quality / sharpness? Any comments or suggestions on other possibilities appreciated. Best wishes Rich

I have the D4 & the D800 and I have found using a 1.4x on my D800 whilst on the 500mm f4 VR renders the image quality very poor…not acceptable for my agency submissions at all.

On my set up there is a huge difference when I take the t/c off. Images are so much sharper, autofocus speed is obviously better and because I’m bare on an f4 lens I can shoot wide open at f4 if I want to during darker light, although I stick to f5.6 generally.

I suspect that the new generation of high MP cameras do not tolerate t/cs like my old D3 or D3S did with ease?

I would love to have 700mm at f5.6 on my D800 & 500mm f4 but never use my t/c now.

Wondering if anyone has experience using the TC-14E or TC-20E III with a DX camera. Specifically I have a D300s and am looking to expand the capabilities of my 70-200mm f/2.8 VR I. The reviews here mention the D4 and D800 but nothing in the DX range.

There is another way of looking at your results, purely in terms of the information captured or conveyed, which is what Imatest is quantifying (as measured in resolution).

With the 1.4X, 1.7X and 2X convertors, you have extracted the following amounts of information from the same area of view (assuming he image quality is equal across the image, which it is usually not). For the 1.4X, you have a ratio of (1-0.05)^2 effective pixels in your area of view, compared to 1/(1.4)^2 in that same area (if you were to upsample). That is ~0.90/0.51 or about 1.77. You have optically extracted about 1.8 times as much information from this area. The corresponding calculations for the 1.7X and 2X yield 1.99 and 2.19. In theory the 2X is extracting the most information, so if your object easily fits within the 2X range, that is where you are getting the most information about it (with information simply being equated with resolution). At 2X, however, the “information” is somewhat smeared out, which makes for less than pixel sharpness. Also, the true information gain for an object in the very middle of the image may be less, since the 70-200 started out sharper in the middle.

In theory, with the 2X image, you might be able to downsample by a factor of about 2 (in pixels, not linear dimensions) to produce something pixel sharp, which, again, if the object fits within the image, would contain twice the information of using the 2X convertor.

That is all theory and requires limiting factors such a sensor movement, to be effectively eliminated in both cases. I am not sure that any of the current software is good enough to use this extra information to effectively get back to a superior print.

I am concerned about one thing. Your tests were all done at 70mm, if I understand correctly. The only logic of using a 1.7X or 2X over a 1.4X is to bring a real jump at the long end, so two more informative lengths to test at might be ~14o and 200.

Does that make sense?

I theory, numbers like these should be released by Nikon with the lens. They will surely have them all in house.

few days back i took a picture of a cricketer with nikon 300/f4 combined with a 20 year old MF nikon 2X CONVERTER.It is available on my flickr photostream (2nd picture)just have a look. i believe that if you depend on AF all the time when converters r in use,it is a bad policy.

Hi Nasim, I shoot sports outdoors and I have Nikon Nikkor f2.8 24 – 70 G – ED. This is the only lens I bought for my d800. I sometimes have to run to the other side of the field to get little closer because i don’t wanna crop the picture. My question is which teleconverter do you recommend for this set up because this is the only lens i am gonna use for a little while. I also don’t wanna lose my wide angle. Any ideas! I mean i do shoot family events too!!

Did you adjust AF fine tune separately for each camera/lens/teleconverter combination? If not, isn’t it possible that this could affect your calculation of image degradation? With my D7100 and 300mm f/4, I get the sharpest images with AF fine tune set to +7 with the 1.4x tc and -6 with the 1.7x. Using the 300mm f/2.8, I get good results with both teleconverters with AF fine tune set to +6. This is just an example of the “idiosyncrasies” of AF behavior with different cameras, lenses, and teleconverters.

Hi I always read Your comments, these are so helpful, so which one of nikon tc’s do you prefer to best combination with d800 and 70-200vr2 consider ing sharpness, AF accuracy and distance approach? I am waiting for your reply to by a nikon tc. Thanks

I was googling information on teleconverters. I am getting into birding and have been using my Nikon D7000 with the 70-300mm VR lens. I would like more reach. I looked at the 80-400mm lens but it’s about $2,600, so I thought maybe a TC would be good to use for taking bird or other animal shot.

Would the 1.4x TC be a good choice? Will it work on my 70-300mm VR lens?

Hi Nasim, That was an interesting article. Yesterday evening I was shooting some motorbike racing with my new Nikon D4s and 200-400 f4 with the TC-17E attached. I noticed that the head on shots of riders exiting a corner were mostly back focused by around 1/2 to 1 meter distance. I was quite shocked initially. However I was also trying to see where the limits of this lens / TC / camera combination lies. I know from a few test shots that the auto focus is much slower at night with the TC17 attached, so I am guessing that shooting a superbike coming towards you at night is asking a lot from this set up. The combination that I am after is one that will enable me to shoot the head-on out of corner shots at the MotoGP next year at Qatar (this being a night race). I did use (a hired) version of this lens last month at Qatar, but without the TC17, there I had no problems, the focus was bang on every time, even in the low light corners.

Hi Nasim, I have a question concerning the 300mm f/4 plus the tc 1.4 ll vs the 500mm f/4, if we give the 500mm an arbitrary score of 100%, what would the 300 plus 1.4 score? What about the 300 plus 1.7? Thanks!

Interesting discussion. I recently acquired a Nikon 300mm f2.8. I did a number of tests to find the ‘sweet spot’ on my D800E. I found the ‘sweet spot’ (the f-stop which provides the greatest sharpness) was f5.6 with just the lens, f6.3 with the 1.4 and 1.7 TCs, and f7.1 with the 2x TC. I agree the TCs slow down the autofocus, and this could be a problem with birds in flight. It is much less of a problem with birds on the water. I also did a test to determine whether it was better to use the TC2 or crop to the equivalent size. I determined that using the TC gave me a better result, again with auto focus speed being taken out of the equation. I am about to conduct similar tests with my D700.

As someone who is looking to invest in a TC for a wildlife solution this is fantastic thread!

I have a D610 and I am looking for a TC to pair with my 70-200 f4. Now I know it isn’t the ideal lens for serious wildlife photography but I don’t have the monies to invest in any new lenses :( And I’m only interested in safari photos and not birds so I suppose I don’t *need* a 500mm prime (would be nice though!). My choices are the 1.4x III or the 1.7x II. I suppose the 2x is ruled out for how slow it makes my lens.

I’m struggling with a couple of points regarding my kit and would really appreciate views.

– While the 1.4x wins on IQ is the 1.7x acceptable if I operate at f8? Will it be fast enough in your collective experience for large-ish mammals? What I go to f6.7 at max zoom. Is the IQ of the 1.7x acceptable? – In general, regardless of the TC I use, is it better to shoot in crop mode or do a manual cropping? I’ve been given both answers by several people and am thoroughly confused! – Would I get a sharper result by using a 1.4x on crop mode / manual cropping or the 1.7x without crop?

Any input would be much appreciated! I have been researching this topic for months and am unable to make up my mind :( I have a safari coming up next month and I want to make the best possible decision under the circumstances!

I can only reply to the cropping question. To me there is a clear answer. I would hardly ever shoot in crop mode unless either you have time to compose your shot (not likely with animals) or you really need that additional fps (e.g. D800). There is nothing as frustrating as having a ruined photo because DX mode cut off too much (happens if you have to hurry, which is the normal case for animals) compared to where the un-cropped photo would have been fine!

I wouldn’t put anything higher than a 1.4 TC on an f/4 zoom. The problem is, that a 1.4x won’t give you much more magnification on a 200mm lens. 280mm is better than nothing though, and with VRIII you should be able to handhold it pretty well. I think a 70-200mm is great for big game when you’re reasonably close and I think a lot of photographers have one while on Safari. 280mm should give you some more opportunities without loosing much performance. The 70-200mm f/4 is an awesome lens though. Much lighter than the f/2.8 so most wildlife photographers I’ve seen use it instead of the 2.8 lens for that reason. Crop later if needed. I second Simon’s opinion on the DX mode.

Good comparison, thanks. I’m wondering what the relative performance would be like just stopped down one stop each and mounted on an f/2.8 prime super-telephoto like they were designed for. This test gives an advantage to the lower magnification TC’s due to being stopped down less. Also, TC’s aren’t really designed for mid-range zooms even though they’ll mount to one. It would be interesting to see what the difference would be, if any, from these results.

Besides the losses in maximum aperture, sharpness and auto-focus quality, do the teleconverters also generate a significant loss in light transmission? I mean, with the same aperture and exposition, will I need a significantly higher ISO? If the answer is yes, can I have an idea of the size of this loss?

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